Increased cold and heat pain thresholds influence the thermal grill illusion in schizophrenia
Version of Record online: 2 JUL 2012
© 2012 European Federation of International Association for the Study of Pain Chapters
European Journal of Pain
Volume 17, Issue 2, pages 200–209, February 2013
How to Cite
Boettger, M.K., Grossmann, D. and Bär, K.-J. (2013), Increased cold and heat pain thresholds influence the thermal grill illusion in schizophrenia. European Journal of Pain, 17: 200–209. doi: 10.1002/j.1532-2149.2012.00188.x
This work was funded in part by the IZKF (Interdiscpiplinary Centre for Clinical Research) of the University Hospital Jena and supported by Deutsche Forschungsgemeinschaft (DFG) BO3235/3-1.
Conflict of interest
There are no potential or actual conflicts of interest for any of the authors regarding this manuscript.
- Issue online: 9 JAN 2013
- Version of Record online: 2 JUL 2012
- Manuscript Accepted: 30 MAY 2012
- IZKF (Interdiscpiplinary Centre for Clinical Research) of the University Hospital Jena
- Deutsche Forschungsgemeinschaft (DFG). Grant Number: BO3235/3-1
Patients with schizophrenia show decreased sensitivity towards clinical and experimental painful conditions. To date, the exact underlying mechanisms are not completely understood. One method to examine central integrative processes of pain perception is the thermal grill illusion (TGI), in which interlacing cold and warm bars create the illusion of a painful sensation.
In 18 unmedicated patients with acute paranoid schizophrenia, cold and heat pain thresholds (CPT/HPT) as well as the perception of the TGI were examined and compared to 18 matched controls. In addition, symptom scales were obtained in order to relate pain perception to psychopathology.
CPT and HPT were significantly increased in patients compared to controls. In the range of TGI stimuli that were perceived painful by controls, patients did not indicate painful sensations, instead the stimulus response curve of TGI pain perception was shifted towards higher stimulus intensities, i.e., greater temperature differentials between cold and warm bars. This increase was comparable to that seen in CPT and HPT. There was no association with psychopathology for any pain parameter.
CPT and HPT, as well as temperature differentials for the perception of the TGI were increased in patients with schizophrenia as compared to controls. Similar to visual illusions, in which reduced contrast sensitivity has been shown to alter the perception of illusions, the discriminatory somatosensory deficit, which is reflected in higher CPT and HPT as well as the previously reported increased warmth perception thresholds, might account for the attenuation of TGI in patients.